Gas Emission Study of the Polyacrylonitrile-Based Continuous Pilot-Scale Carbon Fiber Manufacturing Process

Despite the many positive aspects of carbon fiber arising from its light-weighting potential, high cost and related environmental impact may inhibit even wider usage of the material in future. The need to incinerate gaseous emissions generated during manufacture significantly contributes to both eco-impact and cost, while information regarding these emissions on a production line scale is lacking due to the confidentiality behind commercial carbon fiber manufacturing. A detailed assessment of the evolved gases generated during carbon fiber production and the underlying mechanisms using a state-of-the-art production scale research facility and in situ Fourier transform infrared gas analysis is reported for the first time. A commercially available polyacrylonitrile precursor was converted into carbon fibers, analyzing the most significant exhaust gases from each production step. To identify and quantify the evolved gases during transformation from the precursor to carbon fibers, the evolution of the chemical composition and mass throughout the process was studied. The emissions of HCN, NH3, CO, and CH4 were analyzed and correlated with the changing elemental composition of the processed fibers. Changes in the concentration of specific elements in the fibers were shown to be mirrored by the composition of the gaseous emissions, and responsible chemical mechanisms were introduced.